Because of the number of diseases potentially associated with coughing, the physician must carefully evaluate all anatomic areas that have cough receptors. A complete medical history and physical examination are essential. The medical history provides information concerning the duration of the cough, circumstances of its first appearance, factors influencing it, and its association with sputum production, hoarseness, pain, dyspnea, and other symptoms. General symptoms of disease, such as fever, weight loss, and sweating, are pertinent. A complete history of allergies, environmental exposures, inhalants, and social habits, including smoking and alcohol use, must be obtained.

The physical examination should focus on all mucous membrane surfaces of the ear, nose, neck, and throat. Each region can contribute to the cough reflex. Arnold’s nerve, a branch of the vagus nerve, innervates the floor of the external auditory canal and can be stimulated by the presence of cerumen or the cleaning of cerumen. Examination of the nose and sinuses may detect rhinosinusitis with or without polyps. These entities may cause cough because of postnasal secretions and/or the nasobronchial reflex (trigemminal to vagus nerves). Similar mechanisms may elicit cough in patients with epistaxis and/or nasal packing. Pharyngeal lesions, particularly evidence of gastroesophageal reflux, must be sought during examination to elucidate the cause of the cough. Fiberoptic examination of the sinuses, nasopharynx,
hypopharynx, and larynx is a helpful adjunct to routine examination.

Ancillary diagnostic tests depend in part on the findings of the history and physical examination but generally progress in an orderly sequence as guided by the severity and duration of the cough. The evaluation may include chest radiographs, complete blood cell count, sputum studies (gram stain, cultures, cytologic analysis), and possibly pulmonary function tests, sinus radiographs, allergy tests, and direct endoscopy.

Any pathologic process capable of irritating the sensory receptors in the aforementioned anatomic locations may be responsible for a cough (Table 31-1). An acute cough is defined generally as lasting less than 3 weeks. It is most commonly caused by an upper respiratory tract infection and is self-limited. A chronic cough lasts more than 3 weeks and warrants further investigation.

Definitive treatment depends first on determining the cause and then initiating specific therapy for the underlying disorder (Table 31-1). Antitussive drugs, used for symptomatic relief of coughing, may work centrally as suppressants of the cough center, peripherally by anesthetizing the cough receptors, or through a combination of central and peripheral effects.